LTC3856_15 Datasheet, PDF (5/40 Pages) Linear Technology – 2-Phase Synchronous Step-Down DC/DC Controller with Diffamp

LTC3856
Electrical Characteristics The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T_A = 25°C (Note 2). V_IN = 15V, V_RUN = 5V, unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Differential Amplifier
A_DA
Gain
E-Grade
I-Grade
l 0.998 1 1.002 V/V
l 0.997 1 1.003 V/V
R_IN
V_OS
PSRR
I_CL
V_OUT(MAX)
Input Resistance
Input Offset Voltage
Power Supply Rejection Ratio
Maximum Output Current
Maximum Output Voltage
Measured at DIFFP Input
V_DIFFP = V_DIFFOUT = 1.5V, I_DIFFOUT = 100µA
4.5V < V_IN < 38V
I_DIFFOUT = 300µA
80
kΩ
2
mV
100
dB
2
3
mA
V_INTVCC V_INTVCC
V
–1.4 –1.1
On-Chip Driver
TG R_UP
TG R_DOWN
BG R_UP
BG R_DOWN
GBW
TG Pull-Up R_DS(ON)
TG Pull-Down R_DS(ON)
BG Pull-Up R_DS(ON)
BG Pull-Down R_DS(ON)
Gain-Bandwidth Product
TG High
TG Low
BG High
BG Low
(Note 8)
2.6
Ω
1.5
Ω
2.4
Ω
1.1
Ω
3
MHz
SR
Slew Rate
(Note 8)
2
V/µs
Stage Shedding Mode
I_ISET
Programmable Stage Shedding
Mode Current
6.5 7.5 8.5
µA
AVP (Active Voltage Positioning)
V_AVP
Maximum V_OUT with AVP
I_SINK
Sink Current of AVP Pin
I_SOURCE
Source Current of AVP Pin
V_AVP-V_O(MAX) Maximum Voltage Drop V_AVP to V_O
SENSE⁺ = 1.2V
SENSE⁺ = 1.2V
SENSE⁺ = 1.2V
2.5
V
250
µA
2
mA
120
mV
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3856 is tested under pulse load conditions such that
T_J ≈ T_A. The LTC3856E is guaranteed to meet performance specifications
from 0°C to 85°C operating junction temperature. Specifications over
the –40°C to 125°C operating junction temperature range are assured by
design, characterization and correlation with statistical process controls.
The LTC3856I is guaranteed to meet performance specifications over the
full –40°C to 125°C operating junction temperature range.
Note 3: T_J is calculated from the ambient temperature, T_A, and power
dissipation, P_D, according to the following formula:
LTC3856UH: T_J = T_A + (P_D • 34°C/W)
LTC3856FE: T_J = T_A + (P_D • 25°C/W)
Note 4: The LTC3856 is tested in a feedback loop that servos V_ITH to a
specified voltage and measures the resultant V_FB.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See the Applications Information
section.
Note 6: Rise and fall times are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
Note 7: The minimum on-time condition corresponds to the on inductor
peak-to-peak ripple current ≥40% of I_MAX (see Minimum On-Time
Considerations in the Applications Information section).
Note 8: Guaranteed by design.
3856f